Trig Identities | General Solution | Mlungisi Nkosi

Past exam questions on Trigonometric expressions

[blue_spxrkls]

sine is negative in the fourth quadrant so i think we were supposed to use (360 -ref angle) of which we then divide by 2 to get general solution of x=151, 86+180k etc.

[mosamashatola-hfxs]

SIR ...for a reference angle we dont put the negative sign the negative sine only tell us which quadrants we should consider ..

[rebotilwekgatla]

Your videos are very helpful..thank you 😊

[carmellaiannetti]

Thank you. These are so helpful. I just want to know if the ref angle was negative weren't we suppose to say (360-x) as well as (180+x) ? And also why was -0.84 put in instead of +0.84

[mumtazmahomed]

Hi Mr Nkosi ☺
At time interval 11:11 don't we have to determine where sin is negative and then say sin is negative in the 3rd and 4th quadrant. Thereafter we’ll say 2x=180+Ref angle +k360. And sin is also negative in the 4th quadrant, so we’ll say 2x=360-ref angle+k360. Then solve for x in both equations.

[oratilwesihe]

Guys please help me, I don't understand the last question specifically the first part, wasn't it supposed to be 180+(-57, 14)+k360 then we get the answer of 122, 86 then divide that by the 2 on the side to get an answer of x= 61, 43+k180? Please help coz Im totally lost

[mesulimayeza]

Thank you Malume Mlu.

Isn't our ref angle supposed to be a positive?

[KutlwanoRamasike-enlt]

Sir for our first solution its -28, 57 not -28, 17

[shes.li_melanin]

Am so nervous
Not ready for trigonometry especially the 2D and Euclidean 💔😬

[dimakatsomatlala]

Thank you sir😊. Your videos are helpful. The last question, if I put +0, 84 to find reference angle then check which quad is sine negetive will I be wrong?

Eg.
Sin-1(0, 84)=57.14
2x=180+57.14
=237
x=111.5
And also on 3rd quad❔❓

[mosibuditabudi]

Sir when we solve I thought we don't include the negative angles as it leads us where our solution is in the 4th quadrant where and 3rd where sin is negetive

[phutii]

Why am I only knowing now about that Hence thingy😭💔🤦‍♂️

Thanks👍👍

[zinhlenhlapho]

First to comment😫🎊 These are very helpful sir, thank you very much❤

[shaziapatel]

hi, im confused as to why do we use -1/4Sin2x in the last Q? where does the 2x come from? Shouldn't it just be -1/4SinA like in our above answer?

[BandileMnguni-]

Please sir if I need you how can I find you

[Diemooimeisie]

If your studying right now just leave everything for 5 minutes and ask god for protection wisdom and understanding 🙏🏾 ❤and remember
Through Christ who lives in us we can do everything
May we all excel with great marks ❤

[KiggAnd]

I am requesting t.r mlungis to introduce to me the topic of trigonometry please because lt a new topic to me which l don't understand at all l will be happy lf u reply
😂

[mosamashatola-hfxs]

hence ....i did not know what it mean

[siyamthandambatha]

Maths is so suffocating i fucken hate it.

[dikeledisefala]

Hey, m confused aren't we suppose to check were sin is negative as our angle is negative (180+)and(360-)? E.g 180+28.57 and 360-28.57), I got 28.57as confused